[mythtv-users] Mythweb says I have 75 out of 72 Gigs used

[Shawn Asmussen]

Chris Petersen said:
>> I guess it doesn't read sizes quite right somewhere :)
>> Is this fixed in newer versions?  It's actually an 80 gig drive yet "df
>> -h"
>> shows 76Gigs total and 72Gigs used.
>
> Does mythbackend run as root?  most drives are formatted with a certain
> percentage of space reserved for root's files (to allow root to work and
> fix things if the disk gets full).  df doesn't show this "true" total
> amount.  It's actually a big issue with running mythbackend as root, and
> I keep wishing that someone would write an easy way for mythbackend to
> chuser itself when it starts up (like bind, apache, mysql, etc. do - or
> at least behave)

Which brings up the point that for a filesystem that is dedicated to myth
storage it may make sense to lower or even zero the minfree parameter on
that filesystem (with tunefs -m). If minfree is 0 for that filesystem,
then df will no longer be inaccurate, and if that filesystem is
exclusively for myth storage, there is no particularly compelling reason
to reserve space for root. The tunefs manual page suggests that
performance can be degraded if the filesystem is allowed to fill up beyond
a certain percentage. However, if the backend is running as root, the
minfree parameter isn't preventing the filesystem from filling up anyway.
Also, IMHO, the majority of the performance degradation that would occur
at high usage percentages, is due to fragmentation of the filesystem. With
the type of disk usage that mythtv does, I doubt that a very large amount
of fragmentation is likely even when the drive is nearly filled to
capacity. Of course if the storage area for mythtv isn't on its own
filesystem, things are more complicated.


Shawn Asmussen